The present invention relates to a vehicle control system for controlling a rear wheel steer angle of a vehicle.
A conventional rear wheel steer angle control system is disclosed in Tanaka et al. "Mazda Shasoku Kannougata Yonrinsoda," (Mazda vehicle speed sensing type four wheel steering) 4WS (Yonrinsoda) sha: Active Seigyo Gijutsu no Saizensen, Symposium, Society of Automotive Engineers of JAPAN, 1987. In this conventional system, however, a ratio of a rear wheel steer angle to a front wheel steer angle is constant provided that the vehicle speed is constant. Therefore, this conventional system can improve the vehicle stability in a steady state turning motion, but the improvements in vehicle response characteristic are insufficient especially in an abrupt steering operation as in an emergency, and in a dynamic steering operation as in a traVel along slalom course.